Three new hot hydrogen-deficient pre-white dwarfs
We have detected three new hydrogen-deficient (H < 0.001 mass fraction) pre-white dwarfs (WDs) with helium-dominated atmospheres. The first object is a relatively cool PG1159 star (effective temperature T eff = 72 000 K) that has the lowest surface gravity of any PG1159 star known (log g = 4.8)....
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| Hauptverfasser: | , , , |
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| Dokumenttyp: | Article (Journal) |
| Sprache: | Englisch |
| Veröffentlicht: |
14 January 2025
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| In: |
Astronomy and astrophysics
Year: 2025, Jahrgang: 693, Pages: 1-8 |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/202453197 |
| Online-Zugang: | Verlag, kostenfrei, Volltext: https://doi.org/10.1051/0004-6361/202453197 Verlag, kostenfrei, Volltext: https://www.aanda.org/articles/aa/abs/2025/01/aa53197-24/aa53197-24.html 
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| Verfasserangaben: | Klaus Werner, Nicole Reindl, Max Pritzkuleit, and Stephan Geier |
| Zusammenfassung: | We have detected three new hydrogen-deficient (H < 0.001 mass fraction) pre-white dwarfs (WDs) with helium-dominated atmospheres. The first object is a relatively cool PG1159 star (effective temperature T eff = 72 000 K) that has the lowest surface gravity of any PG1159 star known (log g = 4.8). It is a PG1159 star in the earliest pre-WD phase. The second object is a hot subdwarf O (sdO) star (T eff = 50 000 K, log g = 5.3) with high carbon and oxygen abundances. It is only the third known member of the recently established CO-sdO spectral class, which comprises stars that are thought to be formed by a merger of a disrupted low-mass CO WD with a higher-mass He WD. The third object is one of the rare stars of spectral type O(He) (T eff = 90 000 K, log g = 5.5). |
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| Beschreibung: | Gesehen am 28.07.2025 |
| Beschreibung: | Online Resource |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/202453197 |